Latch mechanism



June 32, 1956 E. c. LANDHOLT 2,750,27

LATCH MECHNISM Filed April 27, 1953 3 Sheets-Sheet l /A/z/f/l/lf ELMER C. LANDHOLT FIG. 5. FIG. 4. /Wmjm/ E. C. LANDHOLT LATCH MECHANISM June 12, 1956 3 Sheets-Sheet 2 Filed April 27, 1953 /A/z/f/l/m? ELMER C. I ANDHOLT June l2, 1956 E. c. LANDHOLT LATCH MECHANISM 5 Sheets-Sheet 3 Filed April 27. 1953 /M/f/z/fm ELMER C. LANoHoL-r 39 3f United States Patent LATCH MECHANISM Elmer C. Landholt, Overland, Mo., assignor to McDonnell Aircraft Corporation, St. Louis, Mo., a corporation of Maryland Application Apni 27, 1953, serial No. 351,115

15 Claims. (Cl. 292-97) This invention relates to latches and is particularly concerned with improvements in latch mechanisms adapted for use on access doors, hatch panels and the like, usually found on and about aircraft of the modern high speed types.

An object of this invention is to construct a latch mechanism which will withstand loads of considerable magnitude applied in any direction in a plane normal to the door surface or normal to the axis of the latch gripping point. e

The object is also to provide a latch mechanism which will withstand constantly shifting loads and directions of load applications without the risk of having the mechanism open or lose its grip.

Another object hereof is to provide a latch mechanism particularly adapted to the functions of pulling an access door or panel into proper closed position to a predetermined contour and to exert a load thereon for resisting forces tending to deect or open the same.

A further object is to provide a latch mechanism having a positive operation to avoid inadvertent unlatching operation under the most severe conditions of service.

An object is to provide a positively operating latch mechanism with an operating handle which has a certain degree of movement independent of the latch mechanism to permit handle pop-out to a convenient position for operating the latch mechanism.

Still another object is to construct a latch having improved means adapting it for application on and in connection with aircraft access doors to provide safety in maintaining these doors in latched condition and to provide for door pull-up and preload operation.

It is an object also to provide latch mechanisms which may be used in multiple on a single door and be capable of remaining in unlatched position so that all of the latches may be handled by one person and the door quickly opened.

Other objects of the present invention reside in the simplicity of the latch construction, in the economical attachment or installation thereof, and in the parts and combination of parts embodied in the latch mechanism.

A preferred latch mechanism adapted for aircraft applications has been herein disclosed, but this is not to be taken as imposing limitation on the more general uses which are possible. In its aircraft use, such a latch must be capable of resisting loads applied generally parallel to the door surface, or loads normal to the door surface, or combinations of both types of loads. Conditions are also encountered in which the loads may vary greatly within an angular range, such as in buleting, vibration, and positive and negative pressure effects due to gun blasts.

The preferred latch mechanism consists in a gripping arm engageable with a xed member, bracket means carried on the movable door or panel and on which the arm is pivoted, and link and lever means operatively connected with the arm for moving the arm positively into ice either its gripping or open positions. The last stated means consists of toggle link members movable through a dead center position into a first arrangement for positive locking actuation of the gripping arm or latch, and into a second arrangement including a part of the latch arm for positive retention of the latch mechanism in unlatched position, and an operating handle connected in lost motion relation to said toggle link member to have the handle pop-out to an easily grasped position and yet avoid inadvertent operation of the toggle mechanism. The invention further consists in the parts and elements, and in the combination of such parts and elements, as will be hereinafter more fully described and set forth in the claims.

In the drawings:

Fig. 1 is a fragmentary elevational view, partly in section, of a latch embodying the present invention;

Fig. 2 is a rear elevational view of Fig. 1 taken along the line 2 2;

Fig. 3 is a detailed transverse sectional view of a portion of the latch taken along line 3-3 in Fig. l;

Fig. 4 is a transverse sectional view similar to Fig. 3, but taken along line 4-4 in Fig. 1;

Fig. 5 is a further transverse sectional view taken along line 5 5 in Fig. l;

Fig. 6 is a front elevational view of the latch shown in Fig. 1;

Fig. 7 is a fragmentary elevational view similar to Fig. 1, but illustrating the latch actuated to its unlatched position;

Fig. 8 is a sectional elevational view through a door and adjacent fixed structure in an aircraft, for example, showing the application of a latch of the character illustrated in Fig. l;

Fig. 9 is a fragmentary elevational view, partly in section, of another form of latch mechanism which embodies the principles of the invention;

Fig. 10 is a detailed sectional view of a portion of the latch of Fig. 9, the view being taken along line 10-10 in Fig. 9;

Fig. 11 is a fragmentary elevational view, partly in section, of yet another form of latch mechanism which embodies the principles of the invention;

Fig. l2 is a fragmentary front elevational view of the latch of Fig. 11, the view being taken along line 12-12 thereof;

Fig. 13 is a diagrammatic illustration of a closure for the opening in a xed structure, showing the present latch operation for pulling the closure into position from a warped attitude relative to the final position desired; and

Fig. 14 is a diagrammatic illustration of a closure for an opening in a lixed structure, the closure having a different warped condition to be overcome by the operation of the latch mechanism.

In Fig. 8, the latch assembly and mechanism 1 is shown mounted near one margin 2 of an access door 3 for closing an opening in the xed structure 4 of an aircraft, while the opposite margin 5 of the door 3 is connected to the structure 4 by a suitable hinge 6, a piano hinge being shown, which allows the door 3 to be swung outwardly of the aircraft. Only one latch mechanism 1 has been shown, but it is contemplated that several such latch mechanisms may be mounted along the margin 2 of this door, according to the requirements of the installation being considered. When a plurality of latches are employed, all latches may be operated by one person, as the latches hold their open or closed positions upon proper operation of the same. The structure 4 includes a door jam or suitable abutment 4' and an internal part 7 to which is fixed a bracket or other means 8 provided with an anchor member or keeper 9. The latch mechanism 1 has a gripping arm 10 in the shape of a hook whose elongated nose 11 passes adjacent the keeper 9 during the latching operation and whose recess finally engages the keeper.

Referring now to Figs. 1 to 5, inclusive, the latch mechanism 1 comprises a pair of side members 13 retained in spaced parallel relation by a pair of spacing sleeves 14 and suitable bolts 15 extending through the members 13 and sleeves 14 and secured by nuts 16. A housing for the latch mechanism 1 is mounted on the rear side of door 3 and comprises longitudinal members 17 and opposite end ribs 18 and 19, respectively. The bolts 15 pass through the housing members 17 (Fig. 2) to secure the latch mechanism in position on the door 3.

The gripping arm is formed as a flat part having the elongated nose 11 formed with a recess 20 which engages the keeper 9 carried by the bracket 8. Arm 10 is pivotally mounted on a pin 21 carried between the side members 13 (Fig. 3), thereby providing opposite arm portions, one defined by the nose 11 and the other shown at 22 between side members 13. Arm 10 is held substantially at the center of pivot pin 21 by a pair of links 23 of similar shape connected on either side of the arm portion 22 (Fig. 3). These links 23 are pivotally connected to the arm portion 22 by a transverse pin 24 extending through one end of the links and the adjacent arm portion. A single link 25 is, in turn, pivotally connected at one end to the opposite end of the links 23 (Fig. 4) by a pin 26, the opposite end of link 25 being pivotally mounted on a fixed pivot pin 27 carried between the side members 13 (Fig. 5). This end of link 25 is substantially centered on pin 27 by spacing sleeves 28 slipped over the pin 27.

The pair of links 23 and single link 25, together with the pivot pins 24, 26 and 27 constitute a toggle link mechanism for positively actuating the arm 10 through the connection with arm portion 22 thereof. In Fig. l, the dead-center axis for the locked arrangement of the toggle mechanism is represented by the reference line A and the longitudinal axes of the links 23 and 25 are represented by reference lines B and C, respectively. Motion of the intermediate pivot pin 26 through its dead-center position (line A) relative to the positions of pins 24 and 27 is assisted by a suitable spring element. The spring has its body portion 29 coiled about one spacer sleeve 28 on pin 27, with one end 30 bearing upon a fixed pin 31 in the side members 13, and its opposite end 32 bearing on the edge of the single link 25 in position to urge the link 25 toward either of its fully angularly displaced or over-center positions for holding the arm 10 in latched or unlatched positions. A second toggle arrangement is formed by the arm portion 22 and links 23, with the pivot 24 (Fig. 7) movable through dead center relative to pivot elements 21 and 26. Toggle actuating means is shown at 35 (Fig. 1) and this means includes a handle lever 37 which operates the toggle link means, opposed by forces on nose 11 and by the force of spring 29. The spring also holds the toggle in the latch open position until the closing operation of lever 37 has carried the pivot 24 past dead center where the spring may then exert its force on the toggle links 23 and 25. In Fig. 7, the second toggle mechanism is shown in its over-center unlatched position, where the spring force applies to assist in holding this position. Here, the dead-center axis for the second arrangement of the toggle mechanism is represented by reference line A and the axes of the links 23 and 22 by the reference lines B and D respectively.

The toggle mechanism thus far described is actuated by a lever 35 which is disposed in an aperture 36 formed in the panel of the access door 3. Lever 35 includes a flat handle portion 37 which in its closed position lies flush within the aperture 36, and is provided with operating means consisting of a pair of side flanges 38 forming a bifurcated portion pivoted on the pin 24 previously described. Each ange 38 has (Fig. l) one edge thereof recessed at 39 to have a lost-motion connection with the intermediate pivot pin 26 of the toggle mechanism. The recess 39 provides end abutment portions 40 and 41 which engage the pin 26 upon opposite movements of the handle 37.

Figs. 1 and 7 illustrate the operation of the present latch. Fig. 1 shows the latch in locked position where link 25 rests against the stop pin 31 to prevent loads on latch 10 moving the links too far and allowing the same to become ineffective. Fig. 7 shows the latch actuated to its unlocked position where the edge of the latch 10 abuts the spacing sleeve 14 as a stop for excessive movement thereof. On comparison of these views of the drawings, it may be seen that the toggle mechanism (Fig. l) has the intermediate pin 26 to the left of the reference axis A and held in this position by pressure exerted on link 25 by the spring arm 32. At this time, the lever 37 may be moved through its lost-motion stroke from the full-line closed position to the broken-line or pop-out position of Fig. 1, without disturbing the toggle mechanism. Motion of arm 37 in a counterclockwise direction, as viewed in Fig. 1, toward the full-line position of Fig. 7 causes the abutment 40 to engage the pin 26 and displace the pin 26 through dead center (to the right of the axis A in the view of Fig. 1), thus causing the links 23 and 25 to assume an angular relationship and concurrently drawing pin 24 toward the fixed pin 27. The spring 29 continues to exert a restoring load upon link 25, but lever 37 provides the necessary advantage to overcome this force. When the latch has been fully opened, pivot pin 24 assumes an over-center position relative to dead center axis A such that the force of spring arm 32 is now exerted along axis B to maintain the toggle in this position. Thus the spring force is effectively resisted and maintains the latch in unlocked position, as in Fig. 7. At this time, the lever 37 may be moved through its lost-motion range between the full line and broken line positions of Fig. 7 without actuating the toggle mechanism.

'I'he outer free end of lever 37 is provided with one part of a keeper or quick detachable device, such as the rotatable stud 44. A suitable socket part 45 is secured between the side members 13 on the inturned flanges 46 thereof (Fig. 5). r[his device may be one of several types which are readily available commercially. Furthermore, a small, light spring, of leaf type, shown at 50 in Figs. 1 and 7 is fixed to the handle 37 and bears against the toggle links 23 to act as a handle raising means to cause the handle to pop out when the fastener stud 44 is turned to disengage its socket 45.

The advantages of the toggle mechanism and actuating handle reside in the quick detachable keeper for the handle, the handle pop-out action by means of the lostmotion provision, the great mechanical advantage of the toggle mechanism in moving arm 10 into and out of gripping engagement with the keeper 9, and the force which may be applied through the handle flanges directly upon the toggle mechanism when the lost motion is taken up. It is noted that the flanges 38 have a fulcrum at pin 24 and a force reaction or abutment at 40 which gives handle 37 the action of a lever upon the pin 26 lifting it through dead center (reference axis A Fig. 1) to over center (reference axis A' Fig. 7). The function of handle 37 and the opposite abutment 41 has the reverse action to that just described when the latch is actuated to latching position. In this instance, the abutment 41 pushes on pin 26 to force it through dead-center position to the position of Fig. 1.

In Fig. 9, the latch assembly is mounted in the housing on the inside of the door 3, as in the first described assembly. The mechanism of this latch is carried by a cast frame 55 fixed to the housing by means of the bolts S6, similar to bolts 15, extending through frame bosses 57 and into the housing sides 17. The cast frame may be made in right and left hand parts, joined along a central face by the bolts 56 to facilitate assembly. The latch arm 60 is pivoted on pin 61 and has the gripping nose 62 with Iits recess 63 engageable with a lixed member or keeper 64 in the bracket 65 carried by a iixed structure (not shown). The arm 60 has an arm portion 66 which is pivotally connected by pin 67 between a pair of links 68 (Fig. 10), and the other ends of the pair of links 68 is pivotally connected by a pin 69 to a single link 70. The link 70 is pivoted at one end to a pin 71 fixed in frame 55, the pin 71 having spacer sleeves 72 on either side of the link 70 to retain it in centered position.

The foregoing links and pivots constitute a pair of toggle mechanisms for actuating the arm 60. Links 68 and 70, and pivot pins 61, 67, 69 and 71 make up the toggle points, wherein motion of pin 69 through a deadcenter line A joining pins 67 and 71 determines the overcenter action of pin 69 in the first arrangement of the toggles. The position of the levers 68 and 70 in Fig. 9 is the locked position relative to arm 60. The line A' represents the dead-center axis of the second arrangement of the toggles. A toggle spring is provided in which the coiled body 74 is mounted on one of the spacer sleeves 72, with one arm 75 bearing on the boss 57 and the 0pposite arm 76 bearing against an edge of link 70 so as to urge the link into the locked position of Fig. 9. The spring has a further body portion 77 carried on the opposite spacer sleeve 72, with one arm 78 forming a continuation of the arm 76 at the bridge portion 79 which forms a hook for the respective arms 76 and 78. The body of spring portion 77 has another arm 80 which is formed with a curved portion 81 encircling the pivot pin 69 adjacent one of the links 68, but free to move Within the limits of the curved portion 81. Of course, the spring body 77 and arm 78 may be separate from the parts 74 and 76.

The toggle mechanism is actuated by a lever 82 pivoted on pin 67 and provided with spaced flanges 83. Each flange 83 has a marginal recess 84 in lost motion association with the pivot pin 69, such lost motion being limited by the end abutments 85 and 86 of the recess 84. The free end of lever 82 is held down by a keeper or quick release fastener having the receptacle 45 for the stud 44 as described in connection with the latch of Fig. 1. When the lever 82 is moved to its closed position, the lost motion limiting abutment 86 urges pin 69 through deadcenter position to establish the locked position of arm 60. At this time the end of link 70 near pin 69 strikes arm portion 66 and the links are effectively stopped from further movement. Upon release of the fastener stud 44, lever 82 will be caused to spring out of its recess 88 in the panel 89 by the motion of spring arm 80 so that it can be grasped to actuate the toggle mechanism, through abutment 85 urging pin 69 through dead center, against spring arm 76. The fully opened latch position is attained when links 68 and 70 are substantially right angularly related, as for the links of the latch in Fig. 7, so that the force of spring arm 76 can be resisted. In this unlatched position, the rear edge of latch 60 held against the stop forming boss 57 by the spring acting over center relative to reference axis A.

In Figs. 1l and 12, the latch mechanism of Fig. 9 has been illustrated with certain changes in the lever thereof to accommodate a lever type quick release keeper device. The toggle lever 92 in Figs. 1l and 12 is pivoted at one end of pin 67 and the opposite end is formed with a lip 93 set below the outer end face thereof. Lip 93 is adapted to be engaged by one margin 102 of a push button lever 94 received in the panel recess 88. The lever 94 is pivoted on pin 95 in the boss 96 of frame 55, and has integral or affixed angularly directed spaced arms 97 located to urge lever 92 outwardly as the lever 94 is pushed inwardly against the force of spring arm 98. The other arm 99 of this spring bears on a fixed pin 100. It can be appreciated that pin 100 also acts as a stop for lever arms 97 to prevent the lever 94 moving too far into the path of lip 93 to prevent return Vof lever 92. The lip 93 has the cam surface 101 which, on closing movement of lever 92, engages the lip 102 on lever 94 and forces lever 94 out of the way so that lip 93 clears lip 102. The lever 94 then snaps back to the position of Fig. 11 where lip 102 becomes the detent for the lever 92 by holding lip 93. To release lever 92, all that is needed is a quick push on lever 94 suiiicient to separate lips 102 and 93, thereafter, spring arm will cause the lever 92 to spring out where it may be grasped.

The foregoing latch mechanisms are particularly useful in aircraft installations because of the range of loads which may be taken thereby from the access door or panel. For example, high air loads on the doors are not easily defined, especially through the transonic and supersonic ranges which may vary the direction and magnitude of resultant loads, as applied to a latch. Therefore one requirement is that the latch must be capable of resisting loads from a direction parallel to the door surface to a direction normal to the surface, as illustrated by the arrows P and N, respectively, in Figs. 13 and 14. This condition becomes aggravated when the door is in an area subjected to the resultant of unpredictable gun blast pressures.

Manufacturing problems usually require acceptances of unwanted warp in doors. The latch must be capable of exerting pull-up to remove this warp and pull the door into a smooth contour iit with surrounding structure for aerodynamic smoothness. This warp may take various forms, two of which are illustrated in Figs. 13 and 14. This warp pull-up is in addition to any structural preload requirements.

Weight considerations in the design of large access doors preclude the possibility of designing the door understructure to resist airloads in bending, therefore structural preload is required to prevent the door from pulling out of contour during hoop tension loading conditions, where the load is in the plane of the door. The latch must then be capable of structural preload of considerable magnitude during latching operation in addition to pull-up for removing door warp. This preload again must be obtained in any plane from parallel with to normal to the door moldline.

In some cases, where the door is small, it is desirable to build into the door a certain amount of warp so that the door can take loads in bending. In these cases, the latch mechanism is required to pull out this manufactured warp.

The latch is rendered safe because it will remain latched even though the operating handle becomes inadvertently disengaged. This is accomplished by an over-center or toggle mechanism entirely independent of the operating handle, as already described. It is also possible to utilize the latch mechanism without the spring such as spring 29 or 74, as the preload tension in the mechanism through the preload on the latch 10 or 60 will develop sufiicient compression in links 23 and 2S, or on link 70 in Fig. 9, to retain the latch in over-center position. However, the springs shown are necessary wherever the forces or loads are transitory and variable in magnitude. Further, if no spring is used, the keeper for the handle will then function as a safety means for preventing unlatching operation, as the abutment 41 (Fig. 1) or abutment 86 (Fig. 9) positively holds the over-center position of the toggle mechanism.

The linkage and latch arrangement of this device is designed to give its best mechanical advantage near the end of the linkage movement for structural preload while using the initial latch movement for door warp pull-up. When finally locked by the overcenter position of the toggle links, it will resist loads in a large segment of loading positions. For example, the nose 11 is rst engageable near its outer end on the keeper 9 which is generally easy toaccomplish by manual effort. Thereafter, the nose 11 moves relative to keeper 9 under the initial closing movement of lever 37 from the broken line position of Fig. 7, to draw the closure 3 from either of the warped conditions of its surface 12', or due to warp purposely manufactured, inwardly and upwardly until the closure is approximately coincident with the moldline 12. The linal motion of the nose 11 to bring the keeper into the recess (Fig. 1) exerts the desired preload upon the closure to stress the latter in hoop tension across the opening. This preload, thus, integrates the closure into the fixed structure 4, so that loads may be carried through the closure.

What is claimed is:

1. Latch mechanism including a supporting structure, a latch movably carried by said structure and having latched and unlatched positions, toggle action link means operatively carried by said structure in position to connect with said latch and said support, and move said latch between the latched and unlatched positions, and manually operable means connected between said latch and link means for actuating said toggle action link means into and out of positions corresponding with the latched and unlatched positions of said latch, said toggle action link means being arranged to be retained when in said latched position by loading conditions on said latch.

2. Latch mechanism for a closure including a latch movable about a xed pivot on the closure, toggle links pivotally interconnected and operatively connected between said latch and the closure, said toggle links and latch having a lirst arrangement in which the links are passed in one direction through dead-center position to move said latch into latched position for the closure, the normal latch loading conditions exerting compression forces in certain of said toggle links for holding the latch in latched position, said toggle links and latch having a second arrangement in which the links are passed in the opposite direction through dead-center position to move said latch into unlatched position for the closure and manually operable means pivoted on said latch and operably connected with said links at the pivotal connection thereof for moving said links through dead-center position.

3. Latch mechanism for a closure for a wall opening and a keeper carried by the wall adjacent the opening, said latch mechanism including a latch pivotally carried by said closure and having a keeper gripping nose portion and an arm portion, a latch operating lever normally tiush with the closure in keeper gripping position of said latch, said lever being pivotally mounted on said latch arm portion, a xed element on said closure spaced from said latch, link means pivotally interconnected and also pivotally connected to and extending between said fixed element and the pivotal mounting of said lever on said latch arm portion, said lever having an operative connection with said link means and said link means being arranged to provide a toggle action locking force upon said latch through lever operation toward flush position in the keeper gripping position thereof, and link operating means on said lever having a lost-motion connection with said link means for relative movement of said lever prior to operation of said link means, said lost motion connection preventing ush positioning of said lever for inelective toggle locking force upon said latch and permitting lifting of said lever out of ush position.

4. Latch mechanism for a closure for a wall having an opening therein, said mechanism including a latch arm pivotally carried by said closure and having an arm portion, a rst link pivotally connected near one end to said arm portion, a second link pivotally connected near one end to the opposite end of said first link and pivotally connected near its opposite end to said closure, said last mentioned pivotal connection of said second link being xed and said first link being movable in space, an actuating lever pivoted on said first mentioned pivotal connection between said arm portion and said first link and movable between a flush position and an outwardly projecting position relative to said closure, operating means on said lever adapted to have lost-motion abutment with said pivotal connection between said links for moving said first link in space between a position with.said lever in ush position and in which said links are relatively extended to exert a toggle holding force upon said latch arm in closure latching position, and in another position with said lever in projecting position and in which said links are relatively folded to pivot said latch arm into a closure unlatching position, and resilient means acting on said second link to retain said links in each of said positions of said latch arm.

5. The combination with a closure for a wall opening and a keeper carried by the wall adjacent the opening, of a latch pivotally carried by said closure for movement between latched and unlatched positions, said latch having a keeper engaging portion which in the latch position exerts a closure pull up force on said keeper lengthwise and perpendicular to the closure, and said latch also having an arm portion, over-center toggle action links operatively connected to said arm portion and the closure, said toggle action links being arranged in the latch position of said latch to be retained in over-center position by the force of said latch'V keeper engaging portion engaging said keeper for holding said latch engaged and certain of said links and said latch arm portion acting in the unlatched position of said latch as an over-center toggle to retain said latch in the latter position.

6. The combination with a pre-warped closure to be latched in a wall opening and a keeper carried by the wall opening, of a latch pivotally carried by the closure including an arm at one side of the pivot and a latch nose at the other side engageable with the keeper to exert a force thereon in the direction of the plane of the wall to pull out the closure pre-warp and draw the closure substantially into the wall plane, toggle action links operatively carried by the closure and connected to said latch arm to move the latch nose portion relative to the keeper and assume latched and unlatched positions, said toggle action links having a relatively extended position substantially at right angles to said latch arm in the keeper engaged position of said latch nose and in latched position by the force of the pre-warped closure on said latch while pulling out the closure pre-warp and an arm on said latch connected to certain of said links and movable through an over-center position to retain said latch in unlatched position.

7. The combination with a warped closure acting as a load carrying part for a wall opening and a keeper carried by the wall adjacent the opening, of a latch pivotally carried by said closure, said latch having a keeper engaging nose and a keeper recess near the nose, a fixed pivot on said closure, toggle links pivotally interconnected and pivotally connected with said latch and said xed pivot, a lever pivotally mounted upon said latch and being operatively connected with said toggle links for selective movement from a position in which said links are angularly related and said latch is free of engagement with the keeper through a position in which said links are longitudinally extended and said latch nose engages the keeper for drawing the warp out of said closure and into a linal position shifting the keeper into said keeper recess for fitting the closure iiush with the wall, and quickly releasable means for securing said lever in said second mentioned position.

8. The combination with a warped closure acting as a load carrying part for a wall opening and a keeper carried by the yvall adjacent the opening, of a latch pivotally carried by said closure, said latch having a keeper engaging nose and a keeper recess near the nose, a xed pivot on said closure, toggle links pivotally interconnected and pivotally connected with said latch and said fixed pivot, a lever pivotally mounted upon said latch and being operatively connected with said toggle links adjacent said pivotal connection with said latch for selective movement, from a position projecting outwardly of said closure in which said links are angularly related at one side of a dead center position and said latch is free of engagement with the keeper, into a position ush with said closure in which said links are longitudinally extended at the other side of said dead center position and said latch nose engages the keeper for drawing the warp out of the closure and the closure flush with the wall opening and shifting the keeper into said keeper recess, resilient means acting on said toggle links to urge said links into angular or extended relation to assist in holding said latch in each of said positions, and quickly releasable means for securing said lever in said second mentioned positions.

9. The combination with a warped closure acting as a load carrying part for a wall opening and a keeper carried by the wall adjacent the opening, of a latch pivotally carried by said closure in position to engage the wall keeper and exert a force on the closure in the plane of the Wall to pull out the warp, said latch having a keeper engaging nose and a keeper recess near the nose, a fixed pivot on said closure, toggle links pivotally interconnected by a rst pivot, one of said links being pivotally connected with said latch by a second pivot and another of said links being connected to said fixed pivot, a lever carried by said latch and being operatively connected with said toggle links for effecting selective movement of said links, from a position in which said links are angularly related with said iirst pivot at one side of a toggle dead center position and said latch is free of engagement with the keeper, into a position in which said links are relatively longitudinally extended with said first pivot at the other side of the toggle dead center position and said latch nose engaged with the keeper for drawing out the closure warp and moving the closure ush with the wall opening and shifting the keeper into said keeper recess, quickly releasable means for securing said lever in said second mentioned position and resilient means acting on said lever to force said lever outwardly of said closure upon actuation of said quickly releasable means to release said lever.

10. The combination with a warped closure acting as a load carrying part for a wall opening and a keeper carried by the wall adjacent the opening, of a latch pivotally carried by said closure, said latch having a keeper engaging nose portion and an arm portion, a xed pivot on said closure, toggle links pivotally interconnected by a rst pivot, one of said links being pivotally connected with said latch arm portion by a second pivot, and another of said links being connected to said fixed pivot, a lever operatively connected with said toggle links for eecting selective movement of said links, from a position in which said links are angularly related at one side of a toggle dead center axis through said second pivot and said xed pivot with said latch free of engagement with the keeper, into a position in which said links are relatively longitudinally extended with said rst pivot at the other side of the toggle dead center axis and said latch nose engaged with the keeper for drawing out the closure warp and moving the closure flush with the wall opening, and quickly releasable means for securing said lever in said second mentioned position, said releasable means including a lever and integral arm pivoted to said closure, a lip on said first lever engageable by said second lever, and resilient means normally holding said second lever in position to engage said lip.

11. Latch mechanism for a warped closure acting as a load carrying part in a wall opening under forces exerted by the latch mechanism upon a keeper carried adjacent the wall opening, said mechanism including a latch pivotally carried by the closure, said latch having a nose engageable with the keeper and a latch operating arm, a pivot carried by the closure, pivotally interconnected toggle links operatively carried between said pivot and said operating arm for operating said latch between an unlatched position in which said latch nose is free of the keeper and a latched position in which said latch nose exerts a force on the keeper and causing the closure to act as a load carrying part in the wall, and operating means for said toggle links including a lever carried by said operating arm and means on said lever having spaced abutments, said means having lost-motion movement adjacent the pivotal interconnection of said links to theextent of said spaced abutments, one of said abutments in the movement of said lever operating said toggle links for unlatching said latch and the other of said abutments operating said toggle links for latching said latch and exerting a force on said nose to reduce the closure warp.

l2. Latch mechanism for a warped closure acting as a load carrying part in a wall opening under forces exerted by the latch mechanism upon a keeper carried adjacent the wall opening, said mechanism including a latch pivotally carried by the closure, said latch having a nose engageable with the keeper and a latch operating arm, a pivot carried by the closure, pivotally interconnected toggle links operatively connected to said pivot carried by the closure and said operating arm for operating said latch between an unlatched position in which said latch nose is free of the keeper and a latched position in which said latch nose exerts a force on the keeper reducing the warp in the closure, lever means pivotally connected to said operating arm, lost-motion means on said lever having spaced abutments located on opposite sides of the pivotal interconnection of said toggle links and having lostmotion movement therewith to the extent of said spaced abutments, one of said abutments operating said toggle links through a toggle dead center axis including said pivot carried by said closure and the pivotal connection of said lever with said operating arm for unlatching said latch, and the other of said abutments forcing said toggle links in an opposite direction for latching said latch and exerting force on the keeper, and spring means acting on said toggle links for holding said links in the unlatched and latched positions of said latch.

13. Latch mechanism for a warped closure acting as a i load carrying part in a wall opening under forces exerted by the latch mechanism upon a keeper carried adjacent the wall opening, said mechanism including a latch pivotally carried by the closure, said latch having a nose engageable with the keeper to transmit forces thereto and a latch recess into which the latch nose directs the keeper, pivotally interconnected toggle links operatively carried by the closure for operating said latch between an unlatched position in which said latch nose is free of the keeper and a latched position in which said latch nose is past the keeper and said latch recess is engaged by the keeper, lever means pivotally connected to said latch, toggle link operating means on said lever having spaced abutments positioned at opposite sides of the pivotal interconnection of said toggle links, said spaced abutments having lostmotion movement therewith, one of said abutments operating said toggle links in a direction for unlatching said latch and the other of said abutments operating said toggle links in an opposite direction for latching said latch and exerting forces thereon to reduce the warp in the cl-osure, holding means carried by said closure in position to be engaged by said lever for holding said lever adjacent the closure in the latched position of said latch, and spring means acting on said lever for moving said lever in the direction of said lost-motion movement for unlatching said latch upon release of said holding means from said lever.

14. Latch mechanism including a supporting structure, a latch movably carried by said structure and having latched and unlatched positions, toggle action link means operatively connected to said structure and to said latch, said link means being pivotally interconnected between said structure and latch to provide relative movement therebetween for moving said latch between the latched and unlatched positions, and means for actuating said link means including a lever pivotally connected to said latch and means carried by said lever having spaced abutments providing lost motion contact between said lever and pivotal interconnection between said link means prior to actuating engagement between said link means and said lever, said lost motion being limited to the latched and unlatched positions of said latch.

15. Latch mechanism including a supporting structure, a latch and integral latch arm means carried by said structure and movable between latched and unlatched positions, pivotally inter-connected toggle action links, a fixed pivot in said structure engaged by a rst one of said links, a pivot in said latch arm engaged by a second one of said links, spring means bearing on one of said links to retain the latter in an extended relation for one limit of toggle displacement corresponding with the latched position of said latch, an operating lever pivoted to said latch arm means, and link operating means on said lever having spaced abutments providing lost motion operating engagement with said pivotal interconnection of said toggle action links, whereby said lever has limited lost motion between 12 said spaced abutments in the latched and unlatched positions of said latch, said links in the unlatched position of said latch having an angular contracted relation and said latch arm and one of said links having a relatively extended position to resist said spring means urging them into opposite extended and contracted relations respectively corresponding with the latched position of said latch.

References Cited in the le of this patent UNITED STATES PATENTS 1,937,978 Miller Dec. 5, 1933 2,477,472 Wright July 26, 1949 2,610,880 Gayner et al Sept. 16, 1952 FOREIGN PATENTS 981,093 France Jan. 10, 1951 

